(1) Field of the Invention
The present invention relates generally to the manufacture of building products and in particular to a novel brick setting method and apparatus for cutting, stacking and setting unfired bricks on a kiln car prior to firing.
(2) Description of the Prior Art
Because of the variability of the raw materials used in the manufacture of bricks, it is inherently difficult to produce a consistant quality end product. Thus, over the years brick manufacturers have resorted to a number of quality control practices to reduce this variability to a minimum. For example, clay pits are carefully mapped out to identify various regions of similar clays in the mine. These regions are selectively mined and stockpiled. At the brick manufacturing plant itself, the raw materials are carefully blended and mixed in order to minimize variation over a period of years. These practices are necessary in order to minimize variations which can occur over a period of years. These practices are necessary in order that builders can match brick in new additions or replacements for a home that was often built ten, twenty, or even thirty years earlier
Assuming that proper steps have been taken in mining, stockpiling, blending and mixing, it is important that the cutting, stacking and setting steps of the brick making process also be carefully controlled to avoid undoing the benefit of the care taken before. As the green bricks are formed and cut, they are typically stacked and restacked several times prior to being fired. This sequence of operations, similar to shuffling a deck of cards, is also critical to minimizing variability.
After forming and stacking, the bricks are loaded onto a kiln car prior to firing. The "green" bricks are set in an open lattice arrangement in order that the bricks on the interior of the brick stack receive a similar heat treatment as the bricks on the exterior of the brick stack. Otherwise, additional product variability will be introduced. Thus, the brick maker's unending task is to reduce or minimize the inherent variability in his craft.
Presently bricks are cut by one of two procedures and set by one of three procedures. In the first cutting method, a continuous slab of clay having cross-sectional dimensions equal to the length and width of a brick is continuously extruded from the pug mill. As the clay slab is extruded, a rotating wire cuts the clay into individual bricks. The bricks then move down an offbearing conveyor to the end of the conveyor where they are assembled into rows of the desired number of bricks. The bricks are then pushed transversely onto a marshalling table where the rows of bricks are stacked in double layers with the upper layer being inverted in an operation called "facing". The double-layer rows are then assembled and delivered by some type of setter head into a kiln car prior to firing.
In the second cutting method, clay slugs are extruded and cut to a prescribed length. The slugs then proceed down the off-bearing conveyor on which they are stacked, one on top of the other, and then pushed through a stationary wire cutter onto a marshalling or spread table. As the slugs are passed through the wire cutter, each slug is cut into a row of bricks in one operation and delivered onto the spread table. As a plurality of rows of bricks are accumulated on the marshalling spread table, a setter head lifts and transfers several double-layer rows at a time onto a kiln car. An example of such a system is disclosed in U. S. Pat. No. 3,589,495 issued to Pearne et al.
In either cutting method, one and sometimes two operations must be performed because of the manner in which the bricks are cut. First, either the slugs or the cut rows of brick must be stacked into double-layer rows or group of rows called "courses". These double-layer rows are subsequently transferred to the kiln car. Secondly, the upper layer of each row may be inverted in an operation called "facing" to protect the finished sides of the bricks as they are fired.
In the previously mentioned Pearne et al patent, the row of slugs are stacked and faced, and then pushed through the wire cutter to form the individual bricks. Pushing a double-layer slug through a wire cutter may cause distortion in the edge of the bricks, as it is difficult to push that size and weight of clay successfully through the wire while making a clean cut. Thus, some systems push only a single layer row of bricks through the wire cutters and then perform the stacking and facing operation afterwards. One system for stacking and facing cut rows of brick subsequent to the cutting operation prior to the delivery of the setter head is disclosed in U. S. Pat. No. 4,326,439 issued to Frost et al.
As previously mentioned, there are three commonly used systems for stacking brick. The first and simplest system involves the formation of rows of pairs of bricks with a lower brick now positioned with its finished face upward and an upper brick row positioned on the lower brick row with its finished face also positioned on the upper side. Such a setting system is usually referred to as "edge setting", "stacking", or "stacking without facing."
The second commonly used system involves inverting the upper brick on the lower brick so that the finished face of the lower brick row engages and supports the finished face of the upper brick row. Such a system is generally referred to as "face setting", and includes the additional steps of inverting previously discussed.
The third system for forming stacks of bricks is known as flat setting. In such a system, rows of two or more bricks rest on each other with the bricks of each row lying on their side so that the brick faces are exposed.
Most prior art inverters and/or stackers have included grippers which grip the brick during the stacking operation. Such gripping often causes damage and results in high scrap rate. Also gripping can cause small fractions in the surface of the brick which are not noticeable which cause brick to deteriorate when water enters and freezes and thaws in use. Some brick stacking systems do not require gripping. One such system which describes an inverter without gripping is shown in U.S. Pat. No. 4,342,531 issued to Cox et al. Another well-known system is shown in U.S. Pat. No. 4,173,910 issued to Lineberry et al. Neither of these systems can selectively face set or stack without facing, however, systems which can edge or flat set are disclosed in U.S. Pat. No. 4,144,977 issued to Lingl et al and U.S. Pat. No. 4,669,968 issued to Milholen.
Because of the multiplicity of the steps in brick making even small gains in efficiency or increases in the flexibility of the process are magnified throughout subsequent steps in the process. For example, in the cutting process of current brickmaking machines, the entire process must be shutdown when the operator switches between 8 inch brick (modular/closures), 10 inch brick (king-size), and 121/2 inch brick (normal). These are nominal dimensions and will vary depending on the shrinkage of the green product during the process. This stoppage is necessary in order that the spacing of the wire cutter can be changed for each style. Since the changeover process can take several hours, there is a need for a cutting apparatus which is readily selectable between more than one size of brick.
In addition to the cutting operation, there is also a need for a quick change over in the stacking/setting operation from either edge or face setting to flat setting, without interferring with the high operating speed of the setting machine operation. Previous machines have either been too slow to perform the sequence of operations or had been unreliable in properly positioning the stacked bricks. Since there are advantages to be had in forming hacks having interspersed courses of both edge or face set and flat set bricks, there is a need for an improved system for reliably performing such an operation. In addition such changes should be achieved automatically by means of program control to provide any desired mixture of edge and flat setting in the brick hack.